The phrase clock doubling implies a clock multiplier of two.
Examples of clock-doubled CPUs include:
- the Intel 80486DX2, which ran at 50 or 66 MHz on a 25 or 33 MHz bus
- the Weitek SPARC POWER µP, a clock-doubled 80 MHz version of the SPARC processor that one could drop into the otherwise 40 MHz SPARCStation 2
In both these cases the overall speed of the systems increased by about 75%.
By the late 1990s almost all high-performance processors (excluding typical embedded systems) run at higher speeds than their external buses, so the term "clock doubling" has lost much of its impact.
For CPU-bound applications, clock doubling will theoretically improve the overall performance of the machine substantially, provided the fetching of data from memory does not prove a bottleneck. In more modern processors where the multiplier greatly exceeds two, the bandwidth and latency of specific memory ICs (and/or the bus or memory controller) typically become a limiting factor.
Read more about this topic: CPU Multiplier
Famous quotes containing the words clock and/or doubling:
“We are hardly ever grateful for a fine clock or watch when it goes right, and we pay attention to it only when it falters, for then we are caught by surprise. It ought to be the other way about.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“My only objection to the arrangements there is the two-in-a-bed system. It is bad.... But let your words and conduct be perfectly pure—such as your mother might know without bringing a blush to your cheek.... If not already mentioned, do not tell your mother of the doubling in bed.”
—Rutherford Birchard Hayes (1822–1893)